US3615829A - Novel carbon compositions methods of production and use - Google Patents

Novel carbon compositions methods of production and use Download PDF

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US3615829A
US3615829A US471097A US3615829DA US3615829A US 3615829 A US3615829 A US 3615829A US 471097 A US471097 A US 471097A US 3615829D A US3615829D A US 3615829DA US 3615829 A US3615829 A US 3615829A
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carbon
char
electrode
chlorine
volts
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James W Sprague
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Standard Oil Co
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/22—Electrodes
    • H01G11/30—Electrodes characterised by their material
    • H01G11/32—Carbon-based
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/22—Electrodes
    • H01G11/30—Electrodes characterised by their material
    • H01G11/48—Conductive polymers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/84—Processes for the manufacture of hybrid or EDL capacitors, or components thereof
    • H01G11/86—Processes for the manufacture of hybrid or EDL capacitors, or components thereof specially adapted for electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/96—Carbon-based electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/13—Energy storage using capacitors
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells

Definitions

  • the resulting 2,494,425 1/ 1959 Bakker 204/130 material contains occluded salts and these may, in a preferred 2,494,425 1/ 1950 Bakkerm 204/ 130 embodiment, be removed.
  • CARBON COMPOSITIONS DEFINED Carbonaceous or carbonizable materials are plentiful in natural fonn. When these materials are heated in the absence of air, several products can be formed depending upon the conditions such as temperature, pressure and the like that are used. The products that can be produced include diamond, graphite, cokes and chars.
  • the carbon compositions of this invention are prepared from those of the above several products which have had a thermal history within the range of about 500 C. to about l,250 C.
  • Particularly useful precursors are chars prepared by heating carbonaceous or carbonizable materials to a temperature in the range from about 500 C. to about l,250 C.
  • Carbonaceous or carbonizable materials occur in many forms including wood, coal, petroleum, pitch, and the like.
  • low-temperature-produced chars prepared from these plentiful substances contain many undesirable impurities, introduced either by absorption, absorption, chemical occlusion or other, which render them relatively useless for many applications including those hereinafter described.
  • these low-temperature carbon chars must be refined and treated to remove the impurities, and/or have materials added to them' either after on concomitantly with purification, to thereby convert them to a more highly useful form.
  • the resulting, unique carbon compositions and a method for their formation constitute an important part of the present invention and provide a substantial advance to the art.
  • novel carbon compositions contemplated by the present invention contain many potential applications including chemical reaction catalysts, sensing elements for electrical control units for both industrial and home utility, and as electrodes in energy storage systems, batteries, capacitors, fuel cells, and the like.
  • novel carbon compositions produced in accordance with the present invention is as an ion absorber and electron conductor in an electrical energy storage device where carbon electrodes have heretofore been used.
  • novel carbon compositions are as electrodes in novel single and multicell capacitor-battery energy storage devices.
  • the novel capacitor-battery storage device possesses the known functional advantages of conventional chemical storage batteries and conventional capacitors but not of their disadvantages.
  • a conventional capacitor is able to store energy quickly on the order of seconds or at most minutes for charging, but suffers the disadvantage that it stores very little energy per unit size.
  • a chemical battery is able to store larger amounts of energy per unit size, but suffers the disadvantage of a relatively slow charging rate.
  • capacitor-batteries as contemplated by the present invention, provide both the quick energy storage characteristic of the conventional capacitor, and the high-level energy storage characteristic of the conventional chemical storage battery.
  • capacitor-batteries have the advantageous characteristics of both conventional capacitors and conventional chemical storage batteries but none of the major defects of these devices. Accordingly, the capacitor-battery device is quickly rechargeable to high levels of energy storage for greater utility than either the conventional capacitor or the conventional chemical storage battery.
  • a further object is to provide a method for producing novel carbon compositions, wherein precursor, activatable chars are converted to modified structures having unexpected utility in the modified state.
  • a further object is to provide novel electrodes for electrical energy storage devices.
  • a further object is to provide a novel capacitor-battery energy storage device.
  • a further object is to provide a novel electrical capacitorbattery utilizing as an electrode or electron-conducting component, a novel carbon composition of invention.
  • a further object is to provide a method for producing novel carbon compositions involving oxidation and reduction of precursor, activatable chars in molten salt electrolytes, whereby materials from the molten salt electrolytes are adsorbed into the carbon structures to render them more highly useful than activatable chars not so treated.
  • a further object is to provide a novel electrical capacitorbattery storage device utilizing an electron conductor of novel carbon composition in combination with a fused salt electrolyte wherein the novel carbon composition is partially produced by pre-use cycling in the cell to cause the occlusion therein of certain elements of the molten salt to produce unexpectedly active electron storage members, surpassing in capacity the prior art analagous members of carbon, wherein it was postulated that surface area was the principal factor contributing to high levels of energy storage.
  • FIG. 1 is a graph illustrating electrode capacity phenomena that have been discovered in accordance with the present invention
  • FIG. 2 is an isometric view, partly broken away in section. of capacitor-battery storage cell made according to the present invention
  • FIG. 3 is an isometric view of a bipolar electrode unit, usable in a cell of the type shown in F IG. 2;
  • FIG. 4 is a graph illustrating electrode capacity phenomena obtained in the run of example 6;
  • WC. 5 is a graph illustrating electrode capacity phenomena observed in the preconditioning of a carbon material to produce products within the scope of the present invention in accordance with example 7, wherein the sweep was made first in the more negative direction;
  • FIG. 6 is a graph illustrating electrode capacity phenomena observed in the preconditioning of a carbon material in accordance with example 7a wherein the sweep was made first in the more positive direction;
  • FIG. 7 is a graph illustrating electrode capacity phenomena observed in the preconditioning of a carbon material in ac cordance with example 7b, wherein the carbon was previously treated by vapor phase chlorination.
  • novel carbon compositions of the present invention can be characterized by the terminology selected carbon polymers". Further, the novel carbon compositions of the present invention can be identified by chemical analysis, and also perhaps equally importantly, as will be discussed hereafter, by the method of production inasmuch as the chemical analysis and method of production seem to be inextricably intertwined with one another.
  • novel carbon compositions of the present invention exist in two forms:
  • Oxidation is used in the broad sense to denote the increase in positive valence or decrease in negative valence of any element in a substance.
  • oxidation is a process in which an element loses electrons.
  • oxidation means the chemical addition of oxygen to a substance.
  • reduction In the broad sense, reduction is the decrease in positive valence or the increase in negative valence of an element. In the narrow sense, reduction means the decrease in the oxygen content, or the increase in the hydrogen content, of a substance.
  • Step I Heating a carbonaceous or carbonizable material in a nonoxidizing atmosphere at a temperature in the range of about 500 to about l,250 C. to form a char.
  • carbons in accordance with the present invention can be made of activated petroleum coke, wood char, activated sodium lignosulfonate char, activated bituminous coal, polyvinylidene chloride char, polyacrylonitrile char and the like.
  • the feature which is common to all of these materials is their low temperature of preparation. None of these carbons has been heated above about 1,l00 C.
  • a lower limit can be set on the temperature of preparation because the carbon must be conducting.
  • Conductivity in chars or carbonized materials ordinarily begins around 600 or 700 C., although in certain specific instances, for example polyvinylidene chloride char, conductivity becomes appreciable at temperatures around 500 C. In a definitive sense then, any polymer carbon that has been prepared between the temperatures of about 500 C. and about 1,250 C. is to be included within the scope of the present invention.
  • these carbons can be characterized by their X- ray diffraction patterns, which are distinctly difi'erent from graphite.
  • Graphite is characterized by very sharp diffraction lines, while the low-temperature polymer carbons are characterized by very difi'use diffraction bands.
  • very flat diffraction patterns which indicated very low crystallite concentration are obtained.
  • the flat patterns of the low-temperature carbons are gradually converted in stages to the crystalline graphite type of diffraction pattern.
  • Step II The selected charcarbon is next pressed and bonded into electrode form.
  • Step III The charcarbon is then treated by both oxidation and reduction to remove therefrom certain occluded impurities such as ash, oxygen, nitrogen, etc. to produce a selected carbon polymer. This can be done by:
  • Oxidizing as contemplated above is to be understood as a reaction conducted in a nonoxygen-containing atmosphere, such as a chlorine gas treatment of the charcarbon in a closed chamber.
  • the oxidationreduction operation can be conducted by cycling the charcarbon electrode in an electrochemical cell or equivalent environment.
  • a cell containing a LiCl-KCI eutectic melt has given good results, other molten salt electrolytes can be used. This cycling accomplishes a two-fold efi'ect on the carbon material as follows:
  • step III of the exemplary method is as follows:
  • the carbon from step II is immersed in a fused lithium chloride-potassium chloride eutectic melt or equivalent electrolyte, at a temperature in the range of about 350 C. to about 0 C.
  • the carbon is for this purpose connected to a source of electrical current and is thus made an electrode in a circuit, another electrode also being immersed in the electrolyte to provide a complete circuit.
  • the electrode is charged in both positive and negative directions.
  • the carbon is charged to at least 0.3 volt with respect to chlorine evolution. From a practical point of view this can be extended to the point at which halogen evolution becomes prohibitive.
  • the carbon is charged to at least 2 volts with respect to chlorine evolution. The negative side can be extended to the 3-volt level.
  • Charging the carbon in the positive direction apparently removes oxygen from the polymer as carbon oxides, both carbon monoxide and carbon dioxide. Hydrogen would also be stripped from the electrode as HCl in a chloride melt or as HBr in a bromide melt.
  • lt is not certain what the effect is when taking the carbon in the negative direction, but an electrochemical reaction does occur between the melt and the chlorinated carbon at some point between about 1 .5 and 2.3 volts. Subsequent reoxidation, when accomplished, puts the carbon in condition for use as an electrode.
  • the charge storage is probably as an electrical double layer, involving primarily adsorption of the anions. From the zero point of charge to more negative potentials, the adsorptions appear to be specific.
  • the shoulder between l and l .5 volts may correspond to removal of covalently bound chlorine, and the maximum at about l.8 to about -2 volts would correspond to the specific adsorption of alkali metal ions.
  • the baked block subsequently was removed from the furnace.
  • a rectangular piece of carbon l X% X% inch was cut from the block and used as a test electrode in an electrochemical cell.
  • the electrolyte in the cell was molten lithium chloride potassium chloride eutectic.
  • Other electrodes in the cell included a graphite tube, bubbling chlorine, used as a chlorine reference electrode, and a Iithium-IOpercent aluminum electrode used as the working electrode or anode.
  • the temperature of the cell was maintained at 500 C.
  • the carbon polymer electrode was initially charged to 0 volta and maintained there for a period of 2 hours. The electrode potential was then adjusted to 3 volts over a period of 1 hour and then brought again to 0 volt over a similar period.
  • the conditioning is carried out at the comparatively high temperature (525 C. and
  • the conditioning is carried out over approximately a 2.8- volt range.
  • the mixture was then transferred to a drying oven and dried for a period of 2 days at a temperature of 230 F.
  • the dried particles were then pulverized in a hammerrnill (running at 16,000 rpm. using a fine (0.02-inch diameter) round hole screen.
  • the resulting powder was mixed with one-quarter of its weight of additional filtchar and this mixture was compressed into a block at a temperature of 150 F. and a die pressure of 8 tons per square inch.
  • the dried block was packed in granular coke in an electric furnace and heated in an atmosphere of argon gas for a period of 45 hours.
  • the heating-cooling cycle was on an automatic 30 curve program with a maximum temperature of 780 C.
  • a pair of electrodes measuring 1 X 'rX 56inch were cut from the baked block and inserted in a cell similar to that described in example 1.
  • One of the carbon electrodes was used to produce a composition of the present invention while the other was used as a working electrode.
  • test electrode was charged initially to volt for a period of 2 hours and subsequently to 3 volts and back to 0 volt over a period of 2 hours.
  • the block was packed in granular coke in an electric furnace and heated at a temperature of 500 C. for a period of 36 hours, then at a temperature of 1,000 C. for a period of 18 hours and finally cooled from 1,000 C. to room temperature over an 18 hour period.
  • a rectangular piece measuring 1 X95 X /4 inch was cut from the baked block and used as a test electrode in an electrochemical cell similar to that described in example 1.
  • both the reference electrode and the working electrode were graphite tubes contained in a larger Pyrex tube.
  • Bottled chlorine gas was bubbled through the graphite tube of the reference electrode.
  • the electrolyte was potassium chloride lithium chloride eutectic.
  • the temperature of the eutectic was maintained at 450 C.
  • EXAMPLE IV Cocoanut Char An electrochemical cell was constructed using a block of carbon obtained from the Pure Carbon Co., St. Mary's, Pa., and designated as Purebon FC-l3, having an average particle size of about 30 microns.
  • the block of carbon was )6 X A X 1 inch and was used as a test electrode in an electrochemical cell.
  • a second electrode of equivalent size was fabricated from lithium-l 8 percent aluminum alloy.
  • the two electrodes were placed in lithium chloride potassium chloride eutectic and connected through an external circuit such that the cell could be charged to maximum voltage and discharged at constant current.
  • the cell was operated with the eutectic maintained at a temperature of 425 C.
  • the lithium-l8 percent aluminum electrode has a potential of 3.36 volts at the 425 C. temperature of the eutectic.
  • the carbon electrode when a cell comprising carbon and aluminum-lithium electrodes is charged to 3.36 volts, the carbon electrode will be at 0 volt. When the cell is discharged to 0.36 volt across the cell, the carbon electrode will be at 3 volts.
  • this cell was discharged from its initial voltage of 1.8 volts to 0.36 volts. Thereafter, the cell was reversed and charged to 3.36 volts. The current at which this operation was conducted was 500 milliamperes.
  • the cell was operated for approximately 15 hours, or approximately 30 cycles.
  • EXAMPLE Cocoanut Char A series was run in which six cells were constructed. Each 25 cell consisted of a chlorine reference electrode and two car- EXAMPLE 6 Hardwood Char A cell was assembled using a test electrode prepared from a 5 commercial carbon obtained from the Purebon Carbon Company, St. Mary's, Pa., designated Purebon FC-50, having an average particle size of about 75 microns. The electrode was A X V4 X 1 inch. The cell also included a working electrode of lithium-l8 percent aluminum, and a chlorine reference elec- 10 trode. Lithium chloride potassium chloride eutectic was used as the electrolyte and was maintained at a temperature of 450 C.
  • test carbon electrode was first charged to --3 volts and subsequently taken to 0 volt over a period of 2% hours on a sweep potentiostat.
  • the temperature of operation was 450 C. 1.5
  • the electrolyte was lithium chloride potassium chloride ll (16 eutectic m IV 4.6
  • the cells were each operated for about l5 hours on a v cycling schedule which consisted of charging to 3 volts across 4x034 g./cc.
  • the cell under constant voltage and then discharging to 1 volt across the cell at a constant current of 500 milliamperes.
  • each of the cells was charged fully. Thereafter, each cell was discharged to a predetermined voltage across the cell. Different cells were discharged to different voltage levels to provide a spread over
  • the capacity versus potential data obtained during the fifth cycle are plotted in graph form in FIG. 4 of the drawings. As shown in FIG. 4, the forward sweep from 0 volt to -3 volts on the test carbon electrode is represented by the solid line.
  • a range corresponding to substantially the full working potenreverse sweep from 3 volts to 0 volt is represented by the tial range of the electrodes.
  • each electrode was then measured with respect to the chlorine reference electrode.
  • the two test electrodes were withdrawn from each cell and analyzed for lithium, potassium, and chloride ion content, using extraction and precipitation techniques. The balance was assumed to be carbon.
  • the analytical results are set forth in table V followdotted line.
  • the graph demonstrates the complete reversability of a reaction which occurs at l.8 volts on the forward sweep.
  • the capacity increases sharply at this point on both the forward and reverse sweeps.
  • N orE Range of analyses on FC-13: Li-36%; K-13-23%; C12535%; C30-60%.
  • EXAMPLE 7 SWEEP FIRST IN MORE NEGATIVE DIRECTION
  • a cell was constructed as in example 6, using a test electrode of Purebon FC-50 carbon, obtained from the Pure Carbon Company, St. Marys, Pa. The cell also included a lithiuml8 percent aluminum working electrode and a chlorine reference electrode. Lithium chloride potassium chloride eutectic was the electrolyte, and the temperature of operation was 450 C.
  • the carbon test electrode was operated on the potentiostatic sweep apparatus at a rate of IO millivolts/minute starting at l.3 volts which was the initial potential of the cell.
  • the gas was collected, analyzed on infrared apparatus, and found to be composed of substantially equal amounts of carbon monoxide and carbon dioxide.
  • a small peak occurs in the region of about 2.7 volts, zone 2.3 volts,
  • FIG. 6 illustrates the results of a run on the order of that conducted in example 7, but with the exception that the sweep was made first in the more positive direction.
  • the reverse sweep was very similar to the reverse sweep of example 7, as shown in FIG. 5, but showed a slightly larger reaction in the l.75-volt region and slightly less reaction in the 0.8-volt region.
  • EXAMPLE 7b CHLORINE TREATMENT Further insight into the method of production can be obtained by treating a raw carbon electrode in an atmosphere of chlorine gas for a period of 1 hour at room temperature.
  • the carbon used was Purebon FC-SO.
  • reaction was similar to that of example 7, as shown in FIG. 5, except that the peak which occurred at 2 volts in example 7, FIG. 5, is shifted to 2.35 volts and is substantially enhanced.
  • Either the chlorine structure or the oxygen structure can be reduced at sufficiently negative potential to produce a totally new material.
  • the chlorine structures are reduced at 2.35 volts while the oxygen structures are reduced at 2.8 volts. These reductions are essentially irreversible. At no time during subsequent cycling are reaction maxima observed that could correspond to these same reactions.
  • the carbon can be reduced electrochemically by charging it to 3 volts; and then oxidizing it by charging it to 0 volt. Alternatively, it may be oxidized by charging to 0 volt and then reduced by charging it to 3 volts.
  • the carbon can first be oxidized in a chlorine atmosphere and then reduced in an electrochemical cell. Presumably this could be extrapolated to a process taking place entirely outside a cell as long as proper energetics for the reactions could be maintained.
  • Novel carbon structure B in the equation above, must still be oxidized to 0 volt or greater, preferably in an electrochemical cell, to produce the final compositions of the present invention. After such treatment, the novel product produced is then reversible on continued cycling, as in an electrochemical storage application.
  • the electrolyte need not be a fused salt.
  • the reactions of the present invention can conceivably be carried out in a nonaqueous solvent containing dissolved lithium or potassium chlorides, for example.
  • electrolytes may be other than the eutectic compositions.
  • novel carbon compositions within the scope of the present invention have been prepared successfully in molten potassium chloride as well as molten lithium chloride. In each of these cases, similar reactions were observed and similar products were obtained.
  • reaction may be carried out, at least to a degree, in fluoride and bromide melts, in addition to chloride melts. lodide melts do not at present appear to be operable.
  • the chloride electrolyte is preferred for two reasons:
  • the carbon electrode is not attacked at an appreciable rate at the most positive potentials attainable.
  • Fluoride melts can be used to oxidize the carbon, but at potentials near 0.3 volts, perfluorocarbons begin to be evolved.
  • Bromide melts do not allow a sufficient degree of oxidation of the carbon structures to give the highest yields of the desired products.
  • the cationic components of the melt may be any or all of the alkali metals (Group la of the Periodic Table), the alkaline earth metals (Group 11A) or the members of Group lllb including the members of the rare earth and actinide contraction series. These materials have in common the property that the cation will not be discharged at an iron or other inert cathode at potentials greater than 2 volts with respect to chlorine. Thus, salts containing these cations will not be decomposed under the conditions of operation of the present invention.
  • EXAMPLE 8 An electrochemical cell was constructed using two electrodes made from Purebon FC-13 carbon of ii X V4 X 1 inchdimension. The cell also included a chlorine reference electrode.
  • the electrolyte was molten potassium chloride.
  • the temperature of operation was 850 C.
  • the cell was operated on a to 3.3-volt span across the cell on a schedule consisting of a constant voltage charge and constant current at 500 milliamps discharge over a 15 hour period (overnight).
  • EXAMPLE 1 l A cell as in example 6 was constructed. This comprised a test electrode of Purebon FC-l3 carbon 52 X A X 1 inch, an anode of lithium 18 percent aluminum and a chlorine reference electrode.
  • the electrolyte was 32 weight percent lithium chloride, 17 weight percent cesium chloride, and the balance potassium chloride.
  • the operating temperature was 450 "C.
  • EXAMPLE 12 A cell as in example 8 was constructed and cycled in the same manner.
  • the electrolyte was lithium chloride-potassium chloride eutectic.
  • the operating temperature was 700C.
  • EXAMPLE 13 A cell was constructed as in example 6, see example 1 I.
  • the electrolyte was 31 weight percent lithium chloride, 5l weight percent potassium chloride, and the balance was rubidium chloride.
  • the operating temperature was 450 C.
  • a cell as in example 8 was constructed and cycled in the 1 12 71 3 9.-
  • the electrolyte was percent lithium chloride 50 percent potassium chloride instead of a lithium chloride potassium chloride eutectic, as in example 12.
  • the operating temperature was 700 C.
  • Example 8 Example 9, LiCl-BaClz CsCl-l'l- LlCl-KCl KCl-5l- N aCl-50 Zone KCl LiOl eutectic K01 melt eutectic RbCl melt KCl I, meq./c.c 0. 3 0. 3 0. 4 0. 6 0. 3 O. 5 0. .3 II, meq./c.c- 0. 2 0. 1 0. 2 0.3 0. 2 0. 3 O. 1 III, meq.lc.c 0. 3 0. 3 0. 7 1. 2 0.6 1. 0 0. .3 IV, meq.lc.c 2. 3 1. 3 1. 9 2. 8 2. 3 2. 7 1. 9 Operating temp., 850 700 650 450 700 450 700 nected as a test electrode to the sweep potentiostat while the electrode that had been maintained most negative was connected as the working electrode.
  • EXAMPLE 9 A cell as in example 8 was constructed and cycled in the same manner.
  • the electrolyte was lithium chloride and the operating temperature was 700 C.
  • EXAMPLE 10 A cell as in example 8 was constructed and cycled in the same manner.
  • the electrolyte was lithium chloride barium chloride eutectic and the operating temperature was 650 C.
  • the electrolyte was lithium chloride potassium chloride eutectic and the operating temperature was 450 C.
  • the electrodes were connected through an external circuit such that the cell could be charged to maximum voltage and discharged at a constant current.
  • the cell was operated on a constant voltage charge to 3.36 volts across the cell and discharged at a constant current of 500 milliamperes down to a level of 0.5 volt across the cell.
  • the cell was cycled for 15 hours (overnight) approximately 30 cycles. Then the discharge for record purpose was taken at 500 milliamperes.
  • the electrodes were then withdrawn from the electrolyte and transferred to fresh electrolyte consisting of a lithium bromide potassium bromide eutectic. Note that this is an all bromide eutectic.
  • the cell was then cycled according to the same schedule. However the charging voltage was reduced to 3.0 volts.
  • zone ll gained capacity at the expense of zone III. This could have certain advantages in some applications particularly in an energy storage device.
  • the cell was cycled for about hours and then a discharge curve was taken for record.
  • the capacity in zone IV was the same as for the electrode of example l5.
  • an electrode prepared and operated in lithium bromide potassium bromide eutectic had the same capacity as an electrode prepared in lithium chloride-potassium chloride eutectic but operated in lithium bromidepotassium bromide eutectic.
  • Temperature Range The results show that the temperature at which the reactions of the present invention can be conducted extend over a substantial range. Similar products have been produced at temperatures from about 400 C. to about 850 C. Temperatures of about 400 C. to about 500 C. are generally preferred for reasons of economy.
  • results show that best energy storage results are produced by first charging in the positive direction to about 0.3 volt relative to chlorine evolution, and subsequently cycling between about 0 volts and about 2.8 volts relative to chlorine evolution.
  • Ash content of the carbon does not appear to have either an advantageous or detrimental effect on the energy storage capacity.
  • the method which is most useful for the study of a carbon structure in a fused salt is a potentiostatic sweep method in which the voltage impressed across the electrode with respect to a reference is continuously and linearly changed as a function of time.
  • the current required to bring the system to the instantaneous potential is a direct measure of the differential capacitance of the test electrode.
  • the capacity measured includes the double-layer capacity along with any pseudocapacity due to reactions which occur either in the carbon surface which could be considered as a part of the double layer, or between constituents of the melt and the electrode surface.
  • the primary reactions involve ions of the melt with the carbon substrate in the region of the electrical double layer.
  • FIG. 1 of the drawings accompanying this application there is illustrated the capacity curve obtained with a pressed activated petroleum coke material according to example I.
  • This particular carbon shows to some degree all of the possible regions of appreciable variation in the capacity curve as a function of electrode potential.
  • the units of the vertical or capacity axis of FIG. 1 are farads per milliliter of electrode.
  • the horizontal or potential axis varies from the chlorine evolution point at 0 volts to 3 volts relative to chlorine evolution.
  • the first zone, at the left side of the curve probably represents the pseudocapacity and double-layer capacity of chloride ion on the electrode surface.
  • the second region conforms to published capacity values for carbon in cryolite, i.e. about 15-20 microfarads per cm. and includes the zero point of charge. (from "Fused Salts", McGraw Hill, 1964, H. A. Laitinen and R. A. Osteryoung, P. 27 l
  • This area II is perhaps the only region in which truly pure double-layer absorption is involved.
  • the third region involves a slight prominence in the curve and may correspond to the desorption of covalently bound chloride.
  • the fourth region is a region of significant alkali metal adsorption occurring near 1 .8 to l .9 volts.
  • the fifth region shows another strong adsorption that occurs at 2.7 volts.
  • regions IV and V correspond to excess alkali on the carbon surfaces or electrochemically reacted and infused into the actual carbon structure.
  • the numbers of adsorbed ions can be calculated. These numbers then can be related to the number of atoms present in the carbon electrode to give a relative population of the carbon atoms per adsorbed ion. This gives an indication of the surface density of charge.
  • the l .9-volt maximum in zone lV corresponds to 46 carbon atoms per ion. At the 2.8 maximum of zone V there is a correspondence to 12 carbon atoms per ion. In terms of concentrations, these figures correspond to about 1.5 and 3.5 milliequivalents per cc. respectively.
  • the quantity of charge in the 1.9-volt region varies somewhat as does the magnitude of the shoulder in the region of chloride desorption.
  • novel carbon materials of the present invention would include electrodes for use in systems other than fused halides in which the pretreatment is conducted. This contemplates that the fused salt residues be removed by simple solvents.
  • the desalted electrodes would be useful in other electromechanical energy storage systems using nonaqueous solvents or lower decomposition potential salt mixtures.
  • novel carbons of the present invention function in accordance with the prior art theory of surface area. At the present, it is not known what the phenomenon involved is. However, it has been found that an unexpectedly high storage capacity for electrical energy is provided by utilizing a novel carbon of this invention as an electron conductor, with the carbon forming an interface component with a nonelectron-conducting medium, such as a fused salt electrolyte.
  • electrical energy is stored to an unexpectedly high order of magnitude substantially greater than that of conventional capacitors of comparable size.
  • FIGS. 2 and 3 Referring now more particularly to FIG. 2, there is shown an electrical energy storage cell embodying an electrode made by the present invention.
  • a container 10 provides a housing for the unit and serves as a storage reservoir for the fused lithium chloride potassium chloride eutectic used as the electrolyte in the system.
  • the container 10 is fabricated of a heat-resistant material capable of withstanding the fused eutectic. This material must be inert relative to the eutectic, of course, and materials such as a nonporous graphite, sheet steel, sheet nickel, stainless steel alloys, ceramics, alumina, etc., will function in this application.
  • any suitable heating means can be utilized, such as immersion heaters or the like.
  • a resistance heater designated by the reference numeral 12.
  • the container 10 is made of an electrically conducting material, it would be understood that the heater 12 must be spaced from it by an insulator. Accordingly, a layer 14 of insulating cement is placed over the outside surface of container 10 prior to the application of the heater 12.
  • Heater l2 suitable comprises a continuous nichrome wire in coil form, wound about the container 10, over the cement layer 14, and thereby spaced from contact with the container 10. It will be understood that the heater 12 could be comprised of flat striptype resistance units as well as the coiled wire mentioned.
  • an external insulation sheath 16 of suitable material such as asbestos or the like.
  • a pair of electrodes 18 and 20 there is provided a pair of electrodes 18 and 20. At least one of the members 18 and 20 is made from a novel carbon composition of the present invention.
  • the electrodes 18 and 20 are maintained in spaced relationship relative to one another by means of a separator member 22.
  • This separator member 22 is suitably formed of a porous nonconductor such as asbestos cloth. Being porous, the member 22 is readily permeated by the ion-containing and conducting medium 11, namely the lithium chloride potassium chloride molten eutectic. It is to be understood that any nonconducting, inert spacing material that is also pervious to the passage of the liquid eutectic can be used for the function of the asbestos cloth unit discussed.
  • Electrical energy current collectors 24 are provided in intimate contacting relationship with the electrodes 18 and 20.
  • the current collectors l4 suitably are formed from graphite compressed into plates. Leads 26 and 28 are connected to and extend from the current collectors 24. These are adapted to be connected either to a charging circuit or to a load such as an electric motor or the like to impart power thereto. It is to be understood that the invention is not limited to the use of graphite in the current collectors 24; accordingly, tantalum metal and the like can be used to serve the current-collecting function.
  • the current 24 are intimately contacted with or joined to the electrodes 18 and 20. This provides an ideal electrical connection for proper functioning of the unit.
  • the electrodes 18 and 20 and the separator member 22 can be fastened together by any suitable means as nonconducting bolts extending through the assembly.
  • v a 7' THE ELECTROLYTE As has been pointed out before, the novel carbon structures of the present invention are derived by an electrochemical oxidation-reduction reaction. This is done in an environment of the energy storage cell illustrated in FIG. 2, which utilizes as one of its components a suitable molten salt of the nature previously set forth.
  • a particularly useful salt mixture is composed of lithium chloride and potassium chloride with the lithium chloride being present at a level of 58.5 mol percent and the potassium chloride being present at a level of 4 l .5-mol percent.
  • This is a eutectic composition and is functionally operable in a temperature range of 350 C. to 1,000 C.
  • This material has a low specific resistivity, 0.6 ohm cm. at 450 C., which produces a low internal resistance of the cell.
  • a step in their production as regards the inclusion therein of at least portions of the molten salt comprises electrochemical charging or treatment of the charcarbon composition after it has been fashioned into the shape of an electrode and actually placed either in an environment simulating an energy storage cell or in an actual storage cell.
  • the treatment comprises the cycling of the electrode over the voltage range from about 0.3 volt relative to chlorine evolution to about 3 volts relative to chlorine evolution. As has been previously mentioned, this imparts a unique character to the carbon material and at the 2.7-volt level a very strong adsorption phenomenon for electron storage takes place. This region is the region of significant alkali metal adsorption; and also a region occurs near 1.8 to l .9 volts, indicating a strongly adsorptive phenomenon.
  • FIG. 3 a unit of the bipolar-electrode-type is illustrated in its basic form.
  • a number of cells constructed as shown in FIG. 3 may he further assembled, by repetition, to provide an electrical storage device of high capacity, applicable to the propulsion of stationary prime movers, or to vehicles of the automotive type, and the like.
  • the bipolar electrode 30 in the center of the unit is of greater thickness than the spaced electrodes 32 and 34 that flank the center electrode. The reason is that the center electrode 30 functions actually as a dual electrode and its storage capacity in volumetric measurement is therefore equivalent to the two electrodes 32 and 34.
  • the outer or flanking electrodes 32 and 34 are maintained in spaced relationship away from the center electrode 30 by nonconducting spacer elements 36. As indicated above, these may be formed from a material such as asbestos cloth.
  • An electrical tapofi is provided from the central dual electrode 30 by means of a lug portion 38 that extends above the top edge, a marginal edge, thereto.
  • a graphite bolt 40 or equivalent is used to provide an electrical connector.
  • lug portions 42 that extend beyond the top edge, or one marginal edge thereof.
  • the lug portions 42 are interconnected electrically by means of a graphite spacer or bridge member 44.
  • a graphite bolt 40 extends through aligned holes in the elements 42, 44, 42 to hold those parts in assembled relationship, providing electrical connection.
  • an insert of the type shown in FIG. 3 actually comprises two cells connected in parallel, with the intermediate plate 30 functioning as a common electrode.
  • a sandwich construction can be produced wherein all of the intermediate electrodes are of the doublethickness type, characterized by element 30 in FIG. 3. Only the outside units would be singles. Thus, in the intermediate portion of a stacked sandwich, all of the double-thickness units would function as bipolar electrodes.
  • the cell units of the present invention lend themselves to connection with cells of similar construction either by connection of a number of cell units in parallel or in series, or by utilization of a stack of electron conductors where the individual electron conductors in the stack are separated by nonconducting spacers, preferably of thin cross section for maximum storage per unit volume.
  • the intennediate electron conductors act in the bipolar capacity, cumulatively adding their respective outputs as if connected in series.
  • a porous, electrically conductive, carbon polymer char body having a zero point of charge at about 0.7 volt, a maximum cation storage capacity in the range of about 1.8 to about -2 volts, a strong adsorption for both alkali metal ions and electron storage at about 2.7 volts, said char containing electrochemically associated therewith at least one cationic component selected from the group consisting of alkali metals, alkaline earth metals, rare earth metals and mixtures of at least two thereof and at least one anionic halogen selected from the group consisting of chlorine, bromine and fluorine, said electrochemically associated char being characterized by its ability to reversibly collect high-capacity charges over a broad electrical potential.
  • An electrical energy storage cell comprising a container for a fused metal salt electrolyte, a fused metal halide salt electrolyte maintained at a temperature ranging from about 350 C. to about l,000 C. said halide selected from the group consisting of chlorine, bromine and fluorine, means for maintaining said temperature, and a plurality of electrodes immersed in said electrolyte at least one of said electrodes comprising a porous, electrically conductive polymer char body according to claim 1.
  • halogen is 6.
  • a char body as in claim 7 having the following approximate concentration of components:
  • a method of making a porous, electrically conductive, carbon polymer char body comprising heating a substantially carbonaceous material at temperatures ranging between about 500 C. and about l,250 C. to convert said material to a porous polymeric carbon char body having diffuse x-ray diffraction bands and low-crystallite concentration and then in any order electrochemically reducing and electrochemically oxidizing said char body, said oxidation being conducted in a nonoxygen-containing medium, by immersing said body in molten salt of halogen anion selected from the group consisting of chlorine, bromine and fluorine and at least one cation selected from the group consisting of alkali metals, alkaline earth metals, rare earth metals and mixtures thereof, said salt being maintained at temperatures of about 350 C. to about 850 C. and electrically charging said immersed body to at least -2 volts in the negative direction relative to chlorine evolution to effect said reduction and charging said immersed body to at least 0.3 volt in the positive direction relative to chlorine evolution to
  • a method as in claim 12 wherein said salt is comprised of the chloride of a plurality of alkali metals including potassium.
  • a method as in claim 12 wherein said charging in the negative direction is to from -2 to 3 volts relative to chlorine evolution.
  • a method as in claim 12 including removing a substantial proportion of said cations by desalting the resulting char body.
  • Col. 19 line 10, after current --connectors-- should be inserted; Col. 19, line 15, after means-such should be inserted; Col. 20, line ll, "thereto” should be --thereof--; and Col. 21, line 27, "25 to 23” should be -l3 to 23- Signed and sealed this 27th day of June 1972.

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  • Chemical & Material Sciences (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • General Chemical & Material Sciences (AREA)
  • Electrochemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Materials Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Carbon And Carbon Compounds (AREA)
  • Battery Electrode And Active Subsutance (AREA)
  • Electrodes For Compound Or Non-Metal Manufacture (AREA)
  • Electric Double-Layer Capacitors Or The Like (AREA)
  • Primary Cells (AREA)
US471097A 1965-07-12 1965-07-12 Novel carbon compositions methods of production and use Expired - Lifetime US3615829A (en)

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Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5225296A (en) * 1989-11-21 1993-07-06 Ricoh Company, Ltd. Electrode and method of producing the same
US5301764A (en) * 1992-04-13 1994-04-12 Gardner Conrad O Hybrid motor vehicle having an electric motor and utilizing an internal combustion engine for fast charge during cruise mode off condition
US5538611A (en) * 1993-05-17 1996-07-23 Marc D. Andelman Planar, flow-through, electric, double-layer capacitor and a method of treating liquids with the capacitor
EP0735554A2 (en) * 1995-03-30 1996-10-02 Isuzu Motors Limited Electrode for electric double layer capacitor and method of manufacturing the same
WO1997046314A1 (en) * 1996-06-07 1997-12-11 Motorola Inc. Carbon electrode material for electrochemical cells and method of making same
US5843393A (en) * 1997-07-28 1998-12-01 Motorola, Inc. Carbon electrode material for electrochemical cells and method of making same
US5876687A (en) * 1997-04-04 1999-03-02 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Elemental metals or oxides distributed on a carbon substrate or self-supported and the manufacturing process using graphite oxide as template
US5972537A (en) * 1997-09-02 1999-10-26 Motorola, Inc. Carbon electrode material for electrochemical cells and method of making same
US20050066573A1 (en) * 2003-09-30 2005-03-31 The Regents Of The University Of California Graphitized-carbon fiber/carbon char fuel
US20080041648A1 (en) * 1992-04-13 2008-02-21 Gardner Conrad O Extended range motor vehicle having ambient pollutant processing
US20100176350A1 (en) * 2005-06-15 2010-07-15 Ut-Battelle, Llc Method of forming an electrically conductive cellulose composite
CN105384170A (zh) * 2015-10-28 2016-03-09 武汉纺织大学 一种在熔盐介质中利用废旧纺织纤维材料制备活性炭的方法
EP3142988A1 (fr) * 2014-05-16 2017-03-22 Carbone Savoie Procédé de préparation d'un matériau composite carboné en vue de son utilisation pour la fabrication de blocs de carbone

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2320413C2 (de) * 1973-04-21 1982-11-11 The Standard Oil Co., 44115 Cleveland, Ohio Verfahren zur Erhöhung der Energiespeicherkapazität einer Elektrode aus amorphem Kohlenstoff
DE3215126A1 (de) * 1982-04-23 1983-10-27 Robert Bosch Gmbh, 7000 Stuttgart Speicherelement fuer elektrische energie
IT1196354B (it) * 1983-12-05 1988-11-16 Dow Chemical Co Dispositivo per l'immagazzinamento di energia elettrica secondaria e elettrodo per esso

Cited By (24)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5225296A (en) * 1989-11-21 1993-07-06 Ricoh Company, Ltd. Electrode and method of producing the same
US5301764A (en) * 1992-04-13 1994-04-12 Gardner Conrad O Hybrid motor vehicle having an electric motor and utilizing an internal combustion engine for fast charge during cruise mode off condition
US5346031A (en) * 1992-04-13 1994-09-13 Gardner Conrad O Hybrid motor vehicle having an electric motor and utilizing an internal combustion engine for fast charge during cruise mode off condition
US20080041648A1 (en) * 1992-04-13 2008-02-21 Gardner Conrad O Extended range motor vehicle having ambient pollutant processing
US20120022736A1 (en) * 1992-04-13 2012-01-26 Conrad Oliver Gardner Extended range motor vehicle having ambient pollutant processing
US5538611A (en) * 1993-05-17 1996-07-23 Marc D. Andelman Planar, flow-through, electric, double-layer capacitor and a method of treating liquids with the capacitor
EP0735554A2 (en) * 1995-03-30 1996-10-02 Isuzu Motors Limited Electrode for electric double layer capacitor and method of manufacturing the same
US5876658A (en) * 1995-03-30 1999-03-02 Isuzu Motors Limited Method for forming electrode using heating and pressurizing of a resin material and the electrode thus formed
EP0735554A3 (en) * 1995-03-30 1997-07-30 Isuzu Motors Ltd Electrode for an electrical double layer capacitor and manufacturing method
WO1997046314A1 (en) * 1996-06-07 1997-12-11 Motorola Inc. Carbon electrode material for electrochemical cells and method of making same
US5876687A (en) * 1997-04-04 1999-03-02 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Elemental metals or oxides distributed on a carbon substrate or self-supported and the manufacturing process using graphite oxide as template
US5948475A (en) * 1997-04-04 1999-09-07 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Elemental metals or oxides distributed on a carbon substrate or self-supported and the manufacturing process using graphite oxide as template
US6039930A (en) * 1997-04-04 2000-03-21 The United States Of America As Represented By Administration Of The National Aeronautics And Space Administration Process for producing metal compounds from graphite oxide
US6103210A (en) * 1997-04-04 2000-08-15 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Process for producing metal compounds from graphite oxide
US5843393A (en) * 1997-07-28 1998-12-01 Motorola, Inc. Carbon electrode material for electrochemical cells and method of making same
WO1999005347A1 (en) * 1997-07-28 1999-02-04 Motorola Inc. Carbon electrode material for electrochemical cells and method of making same
US5972537A (en) * 1997-09-02 1999-10-26 Motorola, Inc. Carbon electrode material for electrochemical cells and method of making same
US7261804B2 (en) * 2003-09-30 2007-08-28 The Regents Of The University Of California Graphitized-carbon fiber/carbon char fuel
US20050066573A1 (en) * 2003-09-30 2005-03-31 The Regents Of The University Of California Graphitized-carbon fiber/carbon char fuel
US20100176350A1 (en) * 2005-06-15 2010-07-15 Ut-Battelle, Llc Method of forming an electrically conductive cellulose composite
US8062868B2 (en) * 2005-06-15 2011-11-22 Ut-Battelle, Llc Method of forming an electrically conductive cellulose composite
EP3142988A1 (fr) * 2014-05-16 2017-03-22 Carbone Savoie Procédé de préparation d'un matériau composite carboné en vue de son utilisation pour la fabrication de blocs de carbone
EP3142988B1 (fr) * 2014-05-16 2023-12-13 Tokai Cobex Savoie Procédé de préparation d'un matériau composite carboné
CN105384170A (zh) * 2015-10-28 2016-03-09 武汉纺织大学 一种在熔盐介质中利用废旧纺织纤维材料制备活性炭的方法

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GB1154083A (en) 1969-06-04
NL133826C (xx)
DE1671108B2 (de) 1977-06-23
BE683882A (xx) 1967-01-09
DE1671108A1 (de) 1971-09-09
IL26038A (en) 1970-05-21
FR1486352A (fr) 1967-06-23
JPS5030810B1 (xx) 1975-10-04
NL6609798A (xx) 1967-01-13

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